U.S. patent application number 11/610552 was filed with the patent office on 2008-06-19 for vehicle hvac system.
This patent application is currently assigned to GM Global Technology Operations, Inc.. Invention is credited to William R. Hill, Gregory A. Major, Edwin J. Stanke.
Application Number | 20080141688 11/610552 |
Document ID | / |
Family ID | 39525496 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080141688 |
Kind Code |
A1 |
Stanke; Edwin J. ; et
al. |
June 19, 2008 |
Vehicle HVAC System
Abstract
A HVAC system and method for a vehicle is disclosed. The air
conditioning portion of the HVAC system may be able to store and
release refrigerant in charge bottle while operating in an air
conditioning mode. The air conditioning portion of the HVAC system
may be able to employ the refrigerant flowing through the
evaporator to provide supplemental heat.
Inventors: |
Stanke; Edwin J.; (Pontiac,
MI) ; Major; Gregory A.; (Farmington Hills, MI)
; Hill; William R.; (Troy, MI) |
Correspondence
Address: |
GENERAL MOTORS CORPORATION;LEGAL STAFF
MAIL CODE 482-C23-B21, P O BOX 300
DETROIT
MI
48265-3000
US
|
Assignee: |
GM Global Technology Operations,
Inc.
Detroit
MI
|
Family ID: |
39525496 |
Appl. No.: |
11/610552 |
Filed: |
December 14, 2006 |
Current U.S.
Class: |
62/149 ;
62/292 |
Current CPC
Class: |
F25B 2345/001 20130101;
F25B 2400/19 20130101; B60H 1/3204 20130101; F25B 45/00
20130101 |
Class at
Publication: |
62/149 ;
62/292 |
International
Class: |
F25B 45/00 20060101
F25B045/00 |
Claims
1. A vehicle HVAC system having an air conditioning portion
comprising: a compressor; a condenser operatively engaging a
refrigerant output from the compressor; an evaporator; an expansion
device operatively engaging a refrigerant output from the condenser
and a refrigerant input to the evaporator; and a charge bottle
selectively connectable to the refrigerant output from the
condenser.
2. The HVAC system of claim 1 including a refrigerant outflow
valve, connected between the charge bottle and the refrigerant
output from the condenser, and operable to be opened to allow a
refrigerant flow into the charge bottle and closed to prevent the
refrigerant flow into the charge bottle.
3. The HVAC system of claim 2 including a refrigerant inflow valve,
connected between the charge bottle and the refrigerant input to
the evaporator, and operable to be opened to allow the refrigerant
flow from the charge bottle and closed to prevent the refrigerant
flow from the charge bottle.
4. The HVAC system of claim 1 including a refrigerant inflow valve,
connected between the charge bottle and the refrigerant input to
the evaporator, and operable to be opened to allow the refrigerant
flow from the charge bottle and closed to prevent the refrigerant
flow from the charge bottle.
5. The HVAC system of claim 4 including a three-way valve,
selectively connectable between the refrigerant output from the
compressor and a refrigerant input to the condenser, and the
refrigerant output from the compressor and the charge bottle.
6. The HVAC system of claim 1 wherein the condenser has a header
and the charge bottle is mounted to the header.
7. The HVAC system of claim 1 wherein the expansion device is a
thermostatic expansion valve.
8. A method of operating a vehicle HVAC system having an air
conditioning portion with a main refrigerant loop, the method
comprising the steps of: (a) determining if air conditioning is
desired; (b) determining if a refrigerant charge is too high; (c)
determining if a refrigerant charge is too low; (d) opening a
refrigerant outflow valve, located between a refrigerant output of
a condenser and a charge bottle, to remove some of the refrigerant
charge from the main refrigerant loop and store it in the charge
bottle, if determined that air conditioning is desired and the
refrigerant charge is too high; and (e) opening a refrigerant
inflow valve, located between a refrigerant input of an evaporator
and the charge bottle, to add some of the refrigerant charge from
the charge bottle into the main refrigerant loop, if determined
that air conditioning is desired and the refrigerant charge is too
low.
9. The method of claim 8 further including the steps of: (f)
determining if supplemental heat is desired; (g) directing a
refrigerant output from a compressor into the charge bottle and
opening the refrigerant inflow valve, if determined that
supplemental heat is desired.
10. The method of claim 9 wherein step (d) is further defined by
closing the outflow valve when refrigerant charge is no longer too
high.
11. The method of claim 9 wherein step (e) is further defined by
closing the inflow valve when the refrigerant charge is no longer
too low.
12. The method of claim 8 wherein step (d) is further defined by
closing the outflow valve when refrigerant charge is no longer too
high.
13. The method of claim 8 wherein step (e) is further defined by
closing the inflow valve when the refrigerant charge is no longer
too low.
14. A method of operating a vehicle HVAC system having an air
conditioning portion with a main refrigerant loop, the method
comprising the steps of: (a) determining if supplemental heat is
desired; (b) directing a refrigerant from a refrigerant output of a
compressor into a refrigerant input to an evaporator, bypassing a
condenser and an expansion device, if determined that supplemental
heat is desired; (c) determining if air conditioning is desired;
and (d) directing a refrigerant from the refrigerant output of the
compressor into a refrigerant input of the condenser, and from a
refrigerant output of the condenser through an expansion device
into the refrigerant input of the evaporator, if determined that
air conditioning is desired.
15. The method of claim 14 wherein steps (b) and (d) are further
defined by providing a three-way valve between the refrigerant
output of the compressor and the refrigerant input of the
condenser.
16. The method of claim 14 further including the steps of (e)
determining if a refrigerant charge is too high, and (f) opening a
refrigerant outflow valve, located between the refrigerant output
of the condenser and a charge bottle, to remove some of the
refrigerant from the main refrigerant loop and store it in the
charge bottle, if determined that air conditioning is desired and
the refrigerant charge is too high.
17. The method of claim 16 further including the steps of (g)
determining if a refrigerant charge is too low, and (h) opening a
refrigerant inflow valve, located between the refrigerant input of
the evaporator and the charge bottle, to add some of the
refrigerant charge from the charge bottle into the main refrigerant
loop, if determined that air conditioning is desired and the
refrigerant charge is too low.
18. The method of claim 17 wherein steps (b) and (d) are further
defined by providing a three-way valve between the refrigerant
output of the compressor and the refrigerant input of the
condenser.
19. The method of claim 14 further including the steps of (e)
determining if a refrigerant charge is too low, and (f) opening a
refrigerant inflow valve, located between the refrigerant input of
the evaporator and the charge bottle, to add some of the
refrigerant charge from the charge bottle into the main refrigerant
loop, if determined that air conditioning is desired and the
refrigerant charge is too low.
20. The method of claim 14 wherein step (b) is further defined by
ceasing operation of the compressor if the supplemental heat is no
longer desired.
Description
BACKGROUND OF THE INVENTION
[0001] The present application relates generally to a heating
ventilating and air conditioning (HVAC) system for a vehicle.
[0002] Conventional vehicle HVAC systems have a refrigeration
circuit and a heating circuit. The conventional refrigeration
circuit includes a compressor, which compresses the refrigerant and
sends it through to a condenser, where heat is removed from the
refrigerant. The refrigerant then flows through an expansion
device, dropping the temperature further, before it enters an
evaporator in an HVAC module of a passenger compartment. The
evaporator absorbs heat from air flowing through it before the air
flows into the passenger compartment. The refrigerant then flows
from the evaporator back into the compressor to start the process
over again. The conventional heating circuit employs a heater core
in the HVAC module in the passenger compartment, where hot coolant
from the engine cooling system flows through it to heat the air
before it flows into the passenger compartment.
[0003] The refrigeration circuit has drawbacks in that, for
refrigerant systems employing expansion valves and receiver dryers,
storing the refrigerant above a critical charge by sub-cooling is
required. The refrigerant storage occurs in the condenser, which
increases the pressure drop in the system and thus reduces the
condenser capacity. This results in reduced system efficiency.
[0004] The heating circuit has drawbacks in that the heater core
cannot provide heat to the air flowing through it until the engine
has time to warm up the coolant. This becomes even more of a
concern as modern engines become more efficient, thus producing
less excess heat to warm up the engine coolant. Electric powered
heaters can be provided for supplemental heating while the coolant
warms up. However, this electric heat may not be very
energy-efficient and may further burden the vehicle electrical
system that may be operating near its capacity in the first
place.
[0005] Thus, it is desirable to provide an HVAC system for a
vehicle that may provide heating or air conditioning in a more
efficient or timely manner.
SUMMARY OF THE INVENTION
[0006] An embodiment contemplates a vehicle HVAC system having an
air conditioning portion that may include a compressor, a condenser
operatively engaging a refrigerant output from the compressor, an
evaporator, and an expansion device operatively engaging a
refrigerant output from the condenser and a refrigerant input to
the evaporator. The embodiment may also include a charge bottle
selectively connectable to the refrigerant output from the
condenser.
[0007] An embodiment contemplates a method of operating a vehicle
HVAC system having an air conditioning portion with a main
refrigerant loop, the method comprising the steps of: determining
if air conditioning is desired; determining if a refrigerant charge
is too high; determining if a refrigerant charge is too low;
opening a refrigerant outflow valve, located between a refrigerant
output of a condenser and a charge bottle, to remove some of the
refrigerant charge from the main refrigerant loop and store it in
the charge bottle, if determined that air conditioning is desired
and the refrigerant charge is too high; and opening a refrigerant
inflow valve, located between a refrigerant input of an evaporator
and the charge bottle, to add some of the refrigerant charge from
the charge bottle into the main refrigerant loop, if determined
that air conditioning is desired and the refrigerant charge is too
low.
[0008] A method of operating a vehicle HVAC system having an air
conditioning portion with a main refrigerant loop, the method
comprising the steps of: determining if supplemental heat is
desired; directing a refrigerant from a refrigerant output of a
compressor into a refrigerant input to an evaporator, bypassing a
condenser and an expansion device, if determined that supplemental
heat is desired; determining if air conditioning is desired; and
directing a refrigerant from the refrigerant output of the
compressor into a refrigerant input of the condenser, and from a
refrigerant output of the condenser through an expansion device
into the refrigerant input of the evaporator, if determined that
air conditioning is desired.
[0009] An advantage of an embodiment may be overall improved
operating efficiency of the refrigerant system, which may allow for
less power consumption. The effective condenser capacity may be
maximized, minimizing the pressure drop across the condenser.
[0010] An advantage of an embodiment may be improved stability in
charge sensitive systems since the appropriate valve can be opened
for short durations when there is excess or insufficient compressor
mass flow capacity.
[0011] An advantage of an embodiment may be to provide the
capability to store reserve cooling charge for short durations.
[0012] An advantage of an embodiment may be the ability of the air
conditioning portion of the HVAC system to provide supplemental
heating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic diagram of an air conditioning system,
with a refrigerant flow path shown for a standard air conditioning
operating mode.
[0014] FIG. 2 is a schematic diagram of a portion of the air
conditioning system of FIG. 1.
[0015] FIG. 3 is a schematic diagram similar to FIG. 1, but showing
a refrigerant flow path when refrigerant is flowing from the main
refrigerant loop into the charge bottle.
[0016] FIG. 4 is a schematic diagram similar to FIG. 1, but showing
a refrigerant flow path when refrigerant is flowing from the charge
bottle into the main refrigerant loop.
[0017] FIG. 5 is a schematic diagram similar to FIG. 1, but showing
refrigerant flow paths for a supplemental heat operating mode.
[0018] FIG. 6 is a flow chart illustrating an overall method for
operating the air conditioning system.
DETAILED DESCRIPTION
[0019] FIG. 1 illustrates a schematic diagram of an air
conditioning portion 20 of an HVAC system 22 for a vehicle 24, with
a refrigerant flow path shown for a standard air conditioning
operating mode. The refrigerant lines with arrows in FIGS. 1 and
3-5 indicate the direction of refrigerant flow for the particular
operating mode illustrated in that figure, while refrigerant lines
without arrows indicate no refrigerant flow through those lines for
that particular operating mode.
[0020] The air conditioning portion 20 may be partially in an
engine compartment 26 and partially in a passenger compartment 28
of the vehicle 24. A compressor 30--typically driven by a vehicle
engine (not shown)--compresses the refrigerant, which then travels
from a refrigerant output of the compressor 30 through a
refrigerant line 32 to a three-way valve 34. The three-way valve 34
connects to a refrigerant line 36 leading to a refrigerant input to
a condenser 38 and to a refrigerant line 40 leading to a charge
bottle 42. The three-way valve 34 is electrically operable to
switch the flow between refrigerant line 36 and refrigerant line
40. A refrigerant line 44 extends from a refrigerant output of the
condenser 38 to a thermostatic expansion valve 46. A refrigerant
line 48 extends from the expansion valve 46 to a refrigerant input
to an evaporator 50, located in an HVAC module 51 in the passenger
compartment 28, and another refrigerant line 52 extends from a
refrigerant output of the evaporator 50 to the expansion valve 46.
Refrigerant line 54 extends from the expansion valve 46 to a
refrigerant input to the compressor 30.
[0021] The expansion valve 46 has a variable orifice that controls
the amount of refrigerant flowing into the evaporator 50, with the
orifice controlled by the pressure and temperature of the
refrigerant leaving the evaporator 50. This is why the expansion
valve 46 is in communication with the refrigerant at both the inlet
and outlet to the evaporator 50.
[0022] The air conditioning portion 20 of the HVAC system 22 also
includes a pair of valves that can be automatically opened and
closed to selectively allow flow to and from the charge bottle 42.
A refrigerant line 56 extends from the charge bottle 42 to a
refrigerant inflow valve 58, and another refrigerant line 60
extends from the refrigerant inflow valve 58 to the inlet to the
evaporator 50. Refrigerant line 62 extends from the charge bottle
42 to a refrigerant outflow valve 64, and another refrigerant line
66 extends from the refrigerant outflow valve 64 to refrigerant
line 44. The term inflow is used relative to valve 58 to indicate
that refrigerant flows from the charge bottle 42 back into the main
refrigerant loop 67 when the inflow valve 58 is open. The term
outflow is used relative to valve 64 to indicate that refrigerant
flows out from the main refrigerant loop 67 into the charge bottle
42 when the outflow valve 64 is open.
[0023] The refrigerant flow path, as indicated by the arrows in
FIG. 1, results from the three-way valve 34 being positioned to
direct flow to the condenser 38, and both the inflow and outflow
valves 58, 64 being closed. This is the refrigerant flow path for a
standard air conditioning operating mode. One will note that, in
this operating mode, there is no flow into or out of the charge
bottle 42--all of the flow is through the main refrigerant loop
67.
[0024] FIG. 2 illustrates a possible packaging arrangement for a
portion of the HVAC system 22 illustrated in FIG. 1. While other
packaging arrangements for the components shown in FIG. 1 can be
used, this packaging arrangement may provide for a relatively
compact and easy to install assembly. The arrangement described in
FIG. 2 has many items in common with that of FIG. 1 and to avoid
unnecessary repetition of the description, the same reference
numerals have been used to refer to the same items, even if not
specifically discussed relative to FIG. 2. The condenser 38 may
include a heat exchanger core 68 and a condenser header 70. The
charge bottle 42 may be mounted to the condenser header 70, with
the three-way valve 34 and the refrigerant inflow valve 58 in close
proximity thereto. The three-way valve 34 may be mounted close to
the condenser refrigerant inlet 72, while the refrigerant outflow
valve 64 may be mounted close to the condenser refrigerant outlet
74. While improving packaging, this arrangement also allows for the
outlet of the charge bottle 42 leading to the refrigerant inflow
valve 58 to be at the bottom of the charge bottle 42. This may
avoid concerns with oil trapping.
[0025] FIG. 3 is a schematic diagram similar to FIG. 1, but
illustrating a refrigerant flow path when the HVAC system 22 is in
the air conditioning operating mode and refrigerant is flowing from
the main refrigerant loop 67 into the charge bottle 42. The
arrangement described in FIG. 3 has the same elements shown as FIG.
1 and to avoid unnecessary repetition of the description, the same
reference numerals have been used to refer to the same elements,
even if not specifically discussed relative to FIG. 3. Removing
some of the refrigerant charge from the main refrigerant loop 67 is
accomplished by positioning the three-way valve 34 to direct flow
through the condenser, leaving the refrigerant inflow valve 58
closed, and opening the refrigerant outflow valve 64 until the
charge is corrected by removing the desired amount of refrigerant
from the main refrigerant loop 67 and storing it in the charge
bottle 42.
[0026] FIG. 4 illustrates a schematic diagram similar to FIG. 1,
but illustrating a refrigerant flow path when the HVAC system 22 is
in the air conditioning operating mode and refrigerant is flowing
from the charge bottle 42 into the main refrigerant loop 67. The
arrangement described in FIG. 4 has the same elements shown as FIG.
1 and to avoid unnecessary repetition of the description, the same
reference numerals have been used to refer to the same elements,
even if not specifically discussed relative to FIG. 4. Adding some
refrigerant charge to the main refrigerant loop 67 is accomplished
by positioning the three-way valve 34 to direct flow through the
condenser, leaving the refrigerant outflow valve 64 closed, and
opening the refrigerant inflow valve 58 until the charge is
corrected by adding the desired amount of refrigerant stored in the
charge bottle 42 to the main refrigerant loop 67.
[0027] FIG. 5 illustrates a schematic diagram similar to FIG. 1,
but illustrating a refrigerant flow path when the HVAC system 22 is
in a supplemental heat operating mode. The arrangement described in
FIG. 5 has the same elements shown as FIG. 1 and to avoid
unnecessary repetition of the description, the same reference
numerals have been used to refer to the same elements, even if not
specifically discussed relative to FIG. 5. Providing supplemental
heat is accomplished by positioning the three-way valve 34 to
direct the refrigerant into the charge bottle 42 rather than
through the condenser 38, opening the refrigerant inflow valve 58
to receive refrigerant from the charge bottle 42 and direct it to
the evaporator 50 (bypassing the expansion valve 46), and leaving
the outflow valve 64 closed.
[0028] FIG. 6 illustrates a possible method for operating the air
conditioning system shown in FIGS. 1-5. A determination is made
whether supplemental heat is desired, block 100. If it is, then the
three-way valve 34 is positioned to bypass the condenser 38 and the
refrigerant inflow valve 58 is opened, block 102, and the
compressor 30 is operated, block 104. If supplemental heat is not
desired, then a determination is made whether air conditioning is
desired, block 106. If not, then compressor operation is ceased,
block 108.
[0029] If air conditioning is desired, a determination is made
whether the refrigerant charge is too high, block 110. If the
refrigerant charge is too high, the three-way valve 34 is
positioned for flow through the condenser 38, the refrigerant
outflow valve 64 is opened, and the compressor 30 is operated while
the refrigerant charge is reduced to the desired level, block 112.
Once the refrigerant charge is reduced to the desired level, the
three-way valve 34 is maintained for flow through the condenser 38,
the outflow valve 64 is closed, block 114, and the compressor 30
continues to operate, block 104.
[0030] If the refrigerant charge is not too high, then a
determination is made whether the refrigerant charge is too low,
block 116. If the refrigerant charge is too low, the three-way
valve 34 is positioned for flow through the condenser 38, the
refrigerant inflow valve 58 is opened, and the compressor 30 is
operated while the refrigerant charge is increased to the desired
level, block 118. Once the refrigerant charge is increased to the
desired level, the three-way valve 34 is maintained for flow
through the condenser 38, the inflow valve 58 is closed, block 114,
and the compressor continues to operate, block 104.
[0031] If the refrigerant charge is not too low, then the three-way
valve 34 is maintained for flow through the condenser 38, both the
inflow and outflow valves 58, 64 are left closed, block 114, and
the compressor 30 is operated, block 104.
[0032] This method allows for maintaining a more desirable amount
of refrigerant charge in the main refrigerant loop 67 during air
conditioning operating mode, which may improve system efficiency at
different ambient and evaporator load conditions. The improved
system efficiency may reduce the work the compressor 30 does, which
may improve vehicle fuel economy. In addition, the valves 34, 58
can be used to bypass the condenser 38, allowing the evaporator 50
to be used to provide supplemental heat.
[0033] An alternative to the system and method embodiments
disclosed above may include, eliminating the charge bottle 42 and
refrigerant outflow valve 64 from the HVAC system 22, and
eliminating the method steps relating to increasing or decreasing
the refrigerant charge in the main refrigerant loop 67. This will
allow for operation in a standard air conditioning mode as well as
a supplemental heat mode, but will eliminate the modes that add or
remove refrigerant from the main refrigerant loop 67. Another
alternative to the system and method embodiments disclosed above
may include eliminating the three-way valve 34 from the HVAC system
22, and eliminating the method steps relating to providing
supplemental heat. This will allow for a standard air conditioning
operating mode, as well as the air conditioning operating modes
that allow refrigerant charge to be removed from or added to the
main refrigerant loop 67. An additional alternative embodiment to
the HVAC system 22 disclosed above may include replacing the
three-way valve 34 with two open/close only valves (not shown).
[0034] While certain embodiments of the present invention have been
described in detail, those familiar with the art to which this
invention relates will recognize various alternative designs and
embodiments for practicing the invention as defined by the
following claims.
* * * * *